The present invention relates to computer software utility programs, and more specifically to selection of a projection plane in computer aided design and computer aided manufacture (CAD/CAM) software systems.
While using CAD/CAM applications it is often desirable to produce two dimensional (2-D) plans representing different views of a three dimensional (3-D) model. Production of 2-D views from the 3-D model can be referred to as generative drafting. One of the difficulties attaching to the generative drafting process is the choice of the most desirable orientations for the drafting views.
In some currently available systems, the selection of the projection plane can be made only on the 3-D model. If a user wishes to change the projection plane, he must revert back to the 3-D model and the system must recompute the 2-D views. Re-computation can take valuable computing time and lead to a loss of productivity. Other systems have included a specific 3-D viewer containing various manipulation commands to avoid this loss of productivity. However, use of the 3-D viewer can also slow down productivity as the user must call the viewer on the screen each time he wants to manipulate the orientation of a projected view.
Other known systems display, by default in the drawing plane, an isometric view of the 3-D model. A user must then define an orientation by the selection of two planes, or edges, with a name of a view he wants to obtain. When the last selection is made, the projection can be computed by the system. Any change in the parameters selected by the user requires the system to generate another projection computation. Such computations can be processor intensive and time consuming.
There is therefore a need for an easy-to-use manipulator which can allow a user to proceed with desired manipulations while staying in the drawing document and to visualize the results of a change of orientation before entering the projection creation command.
Accordingly, the present invention provides a method and apparatus for manipulating a computer generated model and visualizing a change in projection plane before entering a projection creation command.
Once a user has selected a projection plane on the 3-D model in relation with a generative document, the projection plane becomes the plane of the screen. The system can display a visualization of the projection of the model in plane of the screen without generating a fully computed projection. Display of the visualization is more efficient in processing time as compared to a fully computed projection.
The system can also display a graphical manipulator which, in the preferred embodiment, can generally take a form including a circular central region with a button in the middle, wherein clicking on the button can be used as a command to the system requesting creation of the projection.
Generally, in another aspect the graphical manipulator software tool can include quadrants, wherein each quadrant is associated with a direction in relation to an orthogonal axis. A programmable interactive device can correspond with each quadrant and be responsive to activation by a pointing device, such as clicking the button of a mouse. The four quadrants can be defined as left, right, up and down: Clicking on a quadrant can cause the projection plane to rotate by 90xc2x0, or other predetermined amount, around two orthogonal axes of the model in the projection plane. The direction of rotation will correlate with the quadrant selected.
In another aspect a software tool including a pin, or other user interactive device tracking the circumference of a circle can be displayed on a computer screen with a computer generated model. A user can select the pin with a pointing device and rotate it about the displayed circle. Rotation of the pin can cause the projection plane of a computer generated model to rotate about an axis which is perpendicular to the projection screen. In addition, this invention can include an interactive menu for selecting a mode of operation governing the rotation of the pin and the corresponding rotation of the projection plane. In general, rotation options can include free hand rotation, incremental rotation and entering an angle of rotation Activation of the pin can allow a user to obtain all the possible views of the model from which they can select a desired view that can appear on a final drawing. After selection of a desired view, the system can create the full projection.